Rotary Vacuum and Screen System and Methods for Separating Solids and Liquids

ABSTRACT

The invention describes separation systems and methods for separating solids and liquids from one another. The system includes a rotating screen for supporting a slurry of solids and liquid. A fluid manifold is configured to the lower surface of the screen for applying a downward vacuum force through the screen. A cleaning manifold is configured to the screen for cleaning the screen.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/148,163 filed on May 6, 2016, which is a continuation ofInternational Application No. PCT/CA2014/051012 which claims priority toU.S. provisional patent application 61/901,671 filed on Nov. 8, 2013,and U.S. Provisional Patent Application No. 61/940,097 filed on Feb. 14,2014, all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention describes rotary vacuum and screen systems and methods forseparating solids and liquids from one another and in particular drillcuttings from drilling fluid. The systems include a rotating screen thatrotates about an axis of rotation. A fluid manifold is configured to alower surface of the rotating screen for applying a vacuum force throughthe screen. A waste and/or cleaning manifold is configured to anopposite surface of the screen for removing solid materials and/or tocontinuously clean the screen during operation.

BACKGROUND OF THE INVENTION

In the drilling industry, there are various systems used to separatedrilling fluids from drill cuttings that are recovered from rockformations such as an oil well during drilling.

Shale shakers are the primary solids separation tool on a drilling rig.After returning to the surface of the well, the used drilling fluidwhich contains drill cuttings is directed to the shale shakers where themixture of solid cuttings and liquid drilling fluid is processed. Atypical shale shaker includes one or more generally horizontal screenssupported by a frame that is made to vibrate to encourage the separationof drilling fluid from the drill cuttings. The drilling fluid passesthrough the screen where it is deposited into mud tanks either forreturn to the drilling rig for drilling and/or the drilling fluid may besubjected to additional treatment by other solids control equipment toremove finer solids from the recovered drilling fluid. The solids (i.e.drill cuttings) removed by the shale shaker are discharged out of thedischarge port from the top of the screen into a separate holding tankwhere they await further treatment or disposal.

While effective, shale shakers are limited in a number of ways and mostparticularly with respect to the effectiveness of vibration inducedseparation. Under the normal action of a shaker, it is difficult toremove drilling fluid below a level of about 15% wt % of drilling fluidon the cuttings. That is, drill cuttings exiting the shaker willtypically still retain 15-30 wt % of the total mass of recovered drillcuttings as drilling fluid. This amount of drilling fluid not onlyrepresents a significant volume of drilling fluid, it also hasconsiderable value. As a result, it is desirable to minimize thedrilling fluid retained on cuttings at the rig. That is, not only isrecovery of expensive drilling fluid desirable, drill cuttingscontaining a substantial proportion of drilling fluid will requireadditional remediation (and costs) to be incurred prior to finaldisposal. Moreover, drilling fluid that is recovered from drill cuttingscan be returned to the well and can otherwise reduce the overall costsof the drilling fluid program if additional fluid does not have to bepurchased. With costs running in the range of $1000/m³, recovery of anadditional drilling fluid can have significant cost benefits to anoperator.

In addition, the high forces imparted on the drill cuttings by the rapidreciprocating motion of a typical screen bed impart high impact forcesto the cuttings whilst they are on the shaker bed. High impact forcescan cause a degradation of the drill cuttings that will create finerparticles that, depending on their size, will pass through theprocessing screens with the recovered drilling fluid. This creation offinely dispersed particles within the recovered drilling fluid can havevarious adverse affects including increasing the density of the drillingfluid as well as adversely affecting the rheological properties of thedrilling fluid. If the drilling fluid becomes badly degraded, this thenrequires additional solids control processing to remove the fineparticles from the drilling fluid which again adds to the costs of adrilling program.

In the past, vacuum systems have been applied to shale shakers toprovide an additional separation force to the drill cuttings on a shakerbed that has led to improvements in the amount of drilling fluid removedfrom the drill cuttings as well as improving the quality of therecovered drilling fluid. That is, the application of a vacuum force canbe effectively used to remove more drilling fluid and allow the use offiner screens that reduces the amount of fines in the recovered fluid.

However, there continues to be a need for improved separation equipmentand particularly equipment that does not subject the cuttings to thehigh impact forces of a vibrating shaker. In addition, there has been aneed for an effective system to enable separation screens to beeffectively cleaned during use. More specifically, there has been a needfor drilling fluid/drill cuttings separation systems that provide aneffective means of applying a high vacuum pressure to drill cuttingswithout subjecting the drill cuttings to the high impact forces of avibrating screen while continuously cleaning the screen.

SUMMARY OF THE INVENTION

In accordance with the invention, there are provided systems and methodsfor separating solids and liquids from one another and in particulardrill cuttings from drilling fluid.

More specifically, in a first aspect, the invention describes asolids/liquid separation system for separating solids and liquids withina slurry from one another, the separation system including: a screenoperatively connected to a supporting frame, the screen for supportingthe slurry when the screen rotates about an axis of rotation; a fluidmanifold operatively connected to a lower surface of the screen andwherein the fluid manifold is configured to enable a vacuum pressure tobe applied in a first direction and to a first portion of the screenwhile the screen is rotating; and a cleaning manifold operativelyconnected to the screen and wherein the cleaning manifold is configuredto enable an air flow pressure to be applied to a second portion of thescreen in a second direction generally opposite to the first directionwhile the screen is rotating; wherein the vacuum pressure in a firstdirection draws fluid through the screen into the fluid manifold and theair flow pressure in the second direction induces air flow through thescreen in the second direction to clean the rotating screen.

In one embodiment, the screen is operatively supported by a drum and theaxis of rotation is substantially horizontal and corresponds to acentral axis of the drum and the drum has an upstream end and adownstream end and the screen is configured to the drum between theupstream end and the downstream end.

In one embodiment, the fluid manifold is operatively connected to anouter surface of the drum and the fluid manifold is configured to applyan outward vacuum pressure to a lower portion of the screen while thedrum is rotating about the substantially horizontal axis.

In one embodiment, the cleaning manifold includes a waste manifoldoperatively connected to an inner surface of the drum and the wastemanifold is configured to apply an inward vacuum force to a higherportion of the drum relative to a position of the fluid manifold whilethe drum is rotating about the substantially horizontal axis.

In one embodiment, the outward vacuum pressure draws fluid through thescreen into the fluid manifold and stalls solids on the screen and theinward vacuum force through the waste manifold draws stalled solids awayfrom the screen and induces air flow through the screen to clean thescreen.

In another embodiment, the separation system includes a cradle and adrive system for operatively supporting and rotating the drum on thecradle.

In one embodiment, the fluid manifold extends 90-180 degrees around theouter surface of the screen and the screen is operatively connected toan outside surface of the drum or the screen is operatively connected toan inside surface of the drum and the separation system further includesa screen biasing system for biasing the screen against the drum.

In one embodiment, the waste manifold partially overlaps with the fluidmanifold such that during rotation, as a position on the drum moves pastthe fluid manifold, the waste manifold captures material from the innersurface of the drum.

In one embodiment, the separation system includes at least one vacuumsystem operatively connected to each of the fluid and waste manifolds, agas/liquid separator operatively between the fluid manifold and thevacuum system and a gas/solids separator operatively connected betweenthe waste manifold and the vacuum system.

In one embodiment, the separation system includes a pressurized airsystem operatively connected to the fluid manifold for jettingcompressed air against an inner surface of the fluid manifold to assistin the movement of material from inner surfaces of the fluid manifold.

In one embodiment, the separation system includes a pressurized airsystem operatively connected to the waste manifold for jettingcompressed air against an inner surface of the waste manifold to assistin the movement of material from the inner surfaces of the wastemanifold.

In one embodiment, the waste manifold is tapered and wherein theupstream end of the waste manifold has a narrower cross-section and thedownstream end of the waste manifold has a wider cross-section, and thetaper facilitates movement of material through the waste manifold bygravity.

In another embodiment, the cleaning manifold is configured to an outersurface of the drum and a waste manifold is configured to an innersurface of the drum and where the waste manifold is configured to eithera) a downstream portion of the drum and where the waste manifold extendstowards an upstream end from a downstream end of the drum to a position75% or less of the length of the drum or b) a downstream portion of thedrum and where the waste manifold extends towards an upstream end from adownstream end of the drum to a position 50% or less of the length ofthe drum.

In one embodiment, the cleaning manifold is operatively connected to100% of the length of the drum.

In one embodiment, the separation system includes a downstream drumcover operatively connected to the downstream end of the drum and anupstream drum cover operatively connected to the upstream end of thedrum where each of the downstream drum cover and upstream drum coverinclude sealing systems to seal each of the downstream drum cover andupstream drum cover with respect to the drum.

In one embodiment, the system includes an outer cover surrounding theouter surface of the drum wherein each of the cleaning manifold, fluidmanifold and outer cover fully collectively surround the screen andsubstantively seal the drum from the atmosphere.

In one embodiment, exhaust air from the vacuum system is operativelyconnected to the cleaning manifold to provide a source of air to thecleaning manifold.

In one embodiment, the cleaning manifold is open to the atmosphere andair flow into to the cleaning manifold is induced by vacuum pressurethrough the fluid manifold.

In one embodiment, the downstream drum cover includes a solids outletlocated at a bottom location of the downstream drum cover.

In one embodiment, the solids outlet includes at least one baffle withinthe drum operatively positioned to direct solids within the drum to thesolids outlet.

In one embodiment, the downstream drum cover supports a waste manifoldhaving an inner drum portion configured for operative engagement with aninner surface of the drum and an outer conveying portion forconfiguration to a vacuum source.

In another embodiment, the drum is supported by an upstream support ringand a downstream support ring and wherein each of the upstream supportring and downstream support ring include support wheels for engagementwith an outer surface of the drum when the drum is rotating within eachof the upstream and downstream support rings.

In one embodiment, the drum includes an upstream flange and the upstreamsupport ring includes at least one flange support wheel for engagementwith the upstream flange.

In one embodiment, the separation includes at least one upstream drivewheel and at least one downstream drive wheel operatively connected tothe upstream and downstream support rings respectively for engagementwith an outer surface of the drum and for providing a drive force torotate the drum.

In one embodiment, the separation system includes a support frameoperatively connected to the drum and the support frame includes atilting system to enable the drum to be tilted with respect to ahorizontal axis.

In one embodiment, the screen is a rectangular screen having a size forcovering engagement with an outer surface of the drum and wherein thescreen has first and second connecting edges enabling interconnection ofthe first and second connecting edges to tightly engage the screen tothe drum.

In one embodiment, the screen includes at least one screen tie extendingcircumferentially around the drum when the screen is configured to thedrum.

In one embodiment, the drum has at least one recess extendingcircumferentially around the drum and is configured to enable a screentie to engage with the recess when attaching a screen to the drum.

In one embodiment, the separation system includes a distribution plateoperatively connected to the upstream end cover and downstream end coverto enable movement of material within the drum across the drum when thedrum is rotating. The distribution plate may vibrate within the drum.

In one embodiment, the drum includes: a plurality of scoops distributedabout an inner surface of the drum, the scoops being generally parallelto the central axis of the drum for capturing and lifting solids andfluids while the drum is rotating, the drum also including a perforatedsection within each scoop for supporting a screen; and a waste manifoldoperatively connected to an inner surface of the drum and positioned tocapture solids falling from each scoop when a scoop is in an invertedposition within the drum;

In one embodiment, the scoops are substantially longitudinal withrespect to the drum extending from an upstream end of the drum to adownstream end.

In one embodiment, the fluid manifold includes a series of slotsgenerally corresponding in size to each perforated section and whereinduring rotation of the drum each perforated section progressively passeseach slot.

In one embodiment, each scoop has an open end and a longitudinal sidewall having a plurality of perforations, the plurality of perforationsfor providing an additional path to air flow through the scoop.

In one embodiment, the axis of rotation is a substantially vertical axisand the screen is generally horizontal while rotating.

In one embodiment, the screen is circular and the fluid manifold isconfigured to an underside of the screen and extends at least 270degrees around an area of the screen.

In one embodiment, the cleaning manifold is configured to an uppersurface of the screen and removes solid material on the upper surface ofthe screen.

In one embodiment, the separation system includes a drive systemoperatively connected to the screen and frame to effect rotation of thescreen relative to the frame.

In one embodiment, the screen includes a screen support operativelyconnected to the drive system and a replaceable screen adapted forplacement on top of the screen support.

In one embodiment, the screen support includes an outer support flangeadapted for rolling contact with the frame, an inner ring and aplurality of ribs connecting the outer support flange and inner ring andwherein the plurality of ribs support the screen at a level below upperedges of the outer support flange and inner ring to contain the slurryon the replaceable screen during operation.

In one embodiment, the cleaning manifold includes a waste manifoldoperatively connected to an upper surface of the screen and the wastemanifold includes an inlet plenum and a conveying plenum configuredtogether so as to induce cyclonic flow within the conveying plenumduring operation.

In one embodiment, the separation system includes at least one vacuumsystem operatively connected to the fluid and waste manifolds.

In one embodiment, the fluid manifold includes at least one baffle forsectioning the fluid manifold into zones enabling the application ofdifferent vacuum pressures into each zone during operation.

In one embodiment, each baffle includes an upper horizontal plateadapted for sealing with an underside of the screen during rotation ofthe screen with respect to the fluid manifold.

In one embodiment, the fluid manifold includes at least two zones havingseparate outlets and each outlet can include a throttle enabling theadjustment of vacuum pressure within at least one zone.

In one embodiment, the separation system includes a venturi plenumoperatively connected to a lower surface of the screen for directingairflow to a position underneath the waste manifold.

In one embodiment, the system includes an inlet sluice for introducing aslurry of solid/liquid onto the screen. The inlet sluice can include asloping pan for the distribution of slurry across the width of thescreen.

In one embodiment, the inlet sluice includes a large particle entrapmentsystem (LPES) adapted for connection to a lower end of the sloping pan.

In one embodiment, the LPES includes a plurality of parallel tines and astopper bar.

In one embodiment, the separation system includes a cover operativelyconnected to an upper side of the screen.

In one embodiment, the cover includes at least one fluid venturi plenumwithin the cover for directing airflow against a position above thefluid manifold downwardly against the screen.

In one embodiment, the fluid venturi plenum is adjustable with respectto the screen to adjust the separation between the fluid venturi and thescreen.

In one embodiment, the separation system includes a vibration systemoperatively connected to the screen to effect vibration of the screen.In one embodiment, during vibration no vacuum pressure is applied to thescreen.

In another embodiment, a method of separating solid and liquids fromwithin a slurry is provided, includes the steps of: a) introducing theslurry to an upper surface of a screen while the screen is rotatingabout an axis of rotation; b) applying a vacuum force to a portion ofthe lower surface of the screen and in a direction generallyperpendicular to a surface of the screen to draw fluids through thescreen; and, c) applying an air flow pressure to the screen at a secondposition of the screen and in a direction generally opposite to thedirection of flow as defined in step b) relative to the screen to induceair flow through the screen and effect cleaning of the screen.

In one embodiment, the vacuum force is applied to the fluid manifold bya vacuum system, and the method further includes the step of utilizingexhaust air from the vacuum system as a source of air for step c).

In one embodiment, the method includes the step of introducing a portionof the exhaust air from the vacuum system to a burner to effect VOCremoval from the exhaust air.

In one embodiment, the method includes the step of vibrating the screen.

In one embodiment, the separation process defined by steps a)-c) isconducted within a closed system to enable control of heat within thesystem.

In one embodiment, the method includes the step of introducing heat intothe closed system.

In one embodiment, the slurry is a slurry of drilling fluid and drillcuttings and the vacuum force of step b) is sufficient to draw airthrough the rotating screen and effective to reduce drilling fluidretained on drill cuttings to less than 15 wt % (wt. of drilling fluidrelative to wt. of drill cuttings) or to less than 10 wt % (wt. ofdrilling fluid relative to wt. of drill cuttings) or to less than 5 wt %(wt. of drilling fluid relative to wt. of drill cuttings).

In one embodiment, the axis of rotation is generally horizontal, and thescreen is configured to a drum and the method includes the step ofapplying the air flow pressure through a cleaning manifold configured toan outer surface of the drum.

In one embodiment, the vacuum force is applied to the screen by a fluidmanifold operatively connected to an outer surface of the drum and themethod includes the step of applying an outward vacuum pressure to alower portion of the screen while the drum is rotating about thegenerally horizontal axis.

In one embodiment, the cleaning manifold includes a waste manifoldoperatively connected to an inner surface of the drum and the methodincludes the step of applying an inward vacuum force to a higher portionof the drum relative to a position of the fluid manifold while the drumis rotating about the generally horizontal axis.

In one embodiment, the outward vacuum pressure is applied to draw fluidthrough the screen into the fluid manifold and to stall solids on thescreen and the inward vacuum force through the waste manifold drawsstalled solids away from the screen and induces air flow through thescreen to clean the screen.

In one embodiment, the vacuum pressure through the fluid manifold isapplied to 90-180 degrees around the outer surface of the screen.

In one embodiment, the method includes the step of jetting compressedair against an inner surface of the fluid manifold to assist in themovement of material from the inner surfaces of the fluid manifoldand/or the step of jetting compressed air against an inner surface ofthe waste manifold to assist in the movement of material from the innersurfaces of the waste manifold.

In one embodiment, the method includes the step of utilizing exhaust airfrom a vacuum system operatively connected to the fluid manifold as asource of air to the cleaning manifold to clean the screen.

In one embodiment, the method includes the step of tilting theseparation system with respect to a horizontal axis during steps a) toc).

In one embodiment, the method includes the step of providing adistribution plate within the drum to enable movement of material withinthe drum across the drum when the drum is rotating.

In one embodiment, the method includes the step of vibrating thedistribution plate within the drum.

In one embodiment, the axis of rotation is substantially vertical andthe screen is substantially horizontal.

In one embodiment, the air flow force of step c) is sufficient to drawair through the screen to effect solids removal from an upper surface ofthe rotating screen and cleaning of the screen.

In another aspect, the invention provides ascreen assembly for operativeconnection to a separation system, the screen assembly including: aninner support rod for supporting the screen in a roll about the supportrod, the support rod adapted for connection to an exterior surface ofthe separation system adjacent the drum.

In one embodiment, the screen has first and second connecting edgesenabling interconnection of the first and second connecting edges totightly engage the screen to the drum.

In one embodiment, the screen includes at least one screen tieoperatively connected between the first and second connecting edges andextending circumferentially around the drum when the screen isconfigured to the drum.

In yet another aspect, the invention provides method of replacing ascreen in a separation system including the steps of: a) attaching arolled screen assembly having a screen to the separation system adjacentthe outer drum surface; b) attaching a first connecting edge of thescreen to the rotating drum; c) rotating the drum to unroll the rolledscreen assembly; and d)when a second connecting edge of the screen isreached, attaching the second connecting edge of the screen to any oneof or a combination of the first connecting edge and drum such that thescreen is tightly engaged to the outer surface of the drum.

In another aspect, the invention provides a screen assembly foroperative connection to a separation system, the screen assemblyincluding: a screen disk adapted for use on the separation systemwherein the screen has outer dimensions to engage with an outer ring ofthe screen support.

In one embodiment, the screen disk has an inner edge adapted forengagement with the inner ring of the screen support.

In one embodiment, the screen disk includes an upper screen and a lowersupport screen and wherein the upper screen has a smaller pore sizecompared to the lower support screen.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the accompanying figures inwhich:

FIG. 1 is a front perspective view of a rotary tube vacuum (RTV) systemin accordance with one embodiment of the invention without a druminstalled.

FIG. 2 is a second front perspective view of a RTV system in accordancewith one embodiment of the invention with a drum and end coversinstalled.

FIG. 3 is a side perspective view of a RTV system in accordance with oneembodiment of the invention with a drum and end covers installed and adrum cover in an open position.

FIG. 4 is a side view of a RTV system in accordance with one embodimentof the invention with a drum and end covers installed.

FIG. 5 is a rear view of an RTV system in accordance with one embodimentof the invention with a drum and end covers installed.

FIG. 6 is a side view of an RTV system in accordance with one embodimentof the invention with a drum and end covers installed and showing a drumcover in an open position with a screen replacement roll configured.

FIG. 7 is a front view of a RTV system in accordance with one embodimentof the invention with a drum and end covers installed and showing a drumcover in an open position with a screen replacement roll configured.

FIG. 8 is an exploded view of an RTV system in accordance with oneembodiment of the invention showing the primary drum supporting andmanifold components.

FIG. 9 is an exploded view of a waste manifold assembly in accordancewith one embodiment of the invention.

FIG. 10 is a perspective view of a drum in accordance with oneembodiment of the invention.

FIG. 10A is a perspective view of a screen assembly in accordance withone embodiment of the invention.

FIG. 10B is a schematic view of a screen assembly showing a finer screenoverlaying a coarser screen.

FIG. 10C is a perspective view of a screen assembly configured to adrum.

FIG. 10D is a perspective view of a connection system used inconfiguring a screen to a drum in accordance with one embodiment of theinvention.

FIG. 11 is a perspective view of a distribution plate in accordance withone embodiment of the invention.

FIG. 11A is a perspective view of a distribution plate in accordancewith one embodiment of the invention.

FIG. 11B is a cross-sectional view of a distribution plate configuredwithin a drum in accordance with one embodiment of the invention.

FIG. 12 is an exploded view of the assembly of components in accordancewith one embodiment of the invention.

FIG. 13 is a perspective view of an RVT system in accordance withanother embodiment of the invention.

FIG. 14 is a schematic view of a complete RVT and vacuum system inaccordance with one embodiment of the invention.

FIG. 15 is an exploded perspective view of a rotary vacuum table (RVTA)separation system in accordance with one embodiment of the invention.

FIG. 16 is a front perspective view of a RVTA in accordance with oneembodiment of the invention showing a cover in an open position.

FIG. 16A is a front perspective view of a RVTA in accordance with oneembodiment of the invention showing a cover in a closed position. Anoptional vibration system is also shown.

FIG. 16B is a perspective view of a RVTA showing a support system for arotating screen support with a central spindle in accordance with oneembodiment of the invention.

FIG. 16C is a lower perspective view of a RVTA showing a support systemfor a rotating screen support with a central spindle in accordance withone embodiment of the invention.

FIG. 16D is a cross-sectional view of RVTA at line A-A.

FIG. 17 is a perspective view of a fluid manifold of a RVTA inaccordance with one embodiment of the invention.

FIG. 17A is an underside perspective view of a fluid manifold of a RVTAin accordance with one embodiment of the invention.

FIG. 17B is a perspective view of a fluid manifold of a RVTA havingdifferent vacuum zones in accordance with one embodiment of theinvention.

FIG. 17C is a perspective top view of a fluid manifold of a RVTA havingdifferent vacuum zones in accordance with one embodiment of theinvention.

FIG. 17D is a perspective view of a throttle within one vacuum zone of afluid manifold in accordance with one embodiment of the invention.

FIG. 17E is a perspective view of a fluid manifold configured to a framewith the rotating screen support removed.

FIG. 18 is an exploded perspective view of a screen and screen backingin accordance with one embodiment of the invention.

FIG. 19 is a perspective view of a waste manifold of a RVTA inaccordance with one embodiment of the invention.

FIG. 20 is a perspective view of a cover of a RVTA in accordance withone embodiment of the invention.

FIG. 21 is a perspective view of an inflow sluice in accordance with oneembodiment of the invention.

FIG. 22 is a schematic diagram of a deployment of RVTA configured inaccordance with one embodiment of the invention.

FIG. 23 is an exploded diagram showing the assembly of a screen on theinterior of a drum in accordance with one embodiment.

FIG. 24 is a cutaway drawing showing an interior of an RVT with atapered waste manifold in accordance with one embodiment of theinvention.

FIG. 25 is a perspective view of a drill cuttings separator having drumscoops in accordance with an alternate embodiment of the invention.

FIG. 26 is an isometric and cross-sectional view of the embodiment shownin FIG. 25 showing details of the fluid manifold, scoops and wastemanifold.

FIG. 26A is an isometric and cross-sectional view of the embodimentshown in FIG. 25 showing details of the fluid manifold, scoops and wastemanifold with the drum removed.

FIG. 27 is a schematic diagram showing details of the air flow throughthe scoops in accordance with one embodiment of the invention.

FIG. 28 is a perspective view showing details of scoops having bleedholes in accordance with one embodiment of the invention.

FIG. 29 is a schematic diagram showing details of the air flow throughscoops having bleed holes in accordance with one embodiment of theinvention.

FIG. 30 is a perspective diagram of a drum having scoops in accordancewith one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the figures, embodiments of a rotating vacuum systemare described including a rotating vacuum tube (RVT) system and rotatingvacuum table (RVTA) are described. While the RVT and RVTA are describedas a system for separating drilling fluid and drill cuttings, it isunderstood that the systems may be used to separate other fluids/solidsfrom one another. Other embodiments of related separation systems aredescribed in Applicants' co-pending applications including U.S. patentapplication 61/901,671 filed Nov. 8, 2013 and U.S. patent application61/940,097 filed Feb. 14, 2014, incorporated herein by reference.

RVT General Design and Operation

As shown in FIGS. 1-14, a rotating vacuum tube (RVT) system 10 generallyincludes a drum support system 12, a fluid manifold 14, a cleaningmanifold 16 and a cover 18 collectively supporting and covering a drum26. The drum 26 supports a screen and the drum and screen are able torotate together within the system. The system 10 has an upstream end Aand a downstream end B. In the context of this description, a “manifold”is a means for conveying fluids (liquids or gases) from one location toanother. A manifold may have a single inlet or outlet through which thefluids are conveyed or multiple inlets or outlets.

For the purposes of description, positions of the various components inrelation to an end view of the drum, viewed from end B, are described inrelation to clock positions with the topmost position referred to as the12 o'clock position, the bottommost position referred to as the 6o'clock position and the side positions referred to as the 3 o'clock(right) and 9 o'clock (left) positions respectively, shown in romannumerals in FIG. 7.

In operation, a slurry of drill cuttings and drilling fluid isintroduced into the upstream end A of the drum while the drum and screenare rotating. Vacuum pressure is applied to an outside and lower surfaceof the drum/screen through the fluid manifold (typically configured fromabout the 4 o'clock to 9 o'clock positions) so as to draw fluid throughthe screen into the fluid manifold 14. Thus, as the slurry progresseswithin the drum from A to B, fluid is withdrawn from the slurry suchthat solids within the slurry generally become drier as they progresstowards the downstream end B of the drum.

The cleaning manifold 16 is configured to the outside surface of thedrum at approximately the 9-10 o'clock position and applies an airpressure force outside and through the screen and drum during rotation.The cleaning manifold is preferably configured to the full length of thedrum. As such, the entire surface of the screen is subjected to acleaning force with each revolution of the drum.

In one embodiment, a waste manifold 22 a (FIG. 2) is configured to aninside surface of the drum at approximately the 9-10 o'clock position atthe downstream end B of the drum. The waste manifold applies an inwardvacuum pressure to a portion of the screen such that air is drawnthrough the screen and to convey solids away from the inner drum/screensurface. The waste manifold is preferably configured to a portion of thelength of the drum and will therefore only overlap with a portion of thecleaning manifold.

As noted above, while the drum is rotating, the solids will becomeprogressively drier as they move from A to B. Moreover, as they becomedrier, it is desirable to increase the effect of the fluid manifoldvacuum pressure as they travel to maximize fluid removal. In addition,increase fluid manifold vacuum pressure will increase the tendency forthe solids to adhere to the screen and hence be drawn upwardly withinthe drum due to the effect of the fluid manifold vacuum applying anoutward radial pressure to the drier particles. At approximately the 9o'clock position, the fluid manifold vacuum pressure will cease and thematerial will be subjected to forces from the cleaning manifold 16. Inaddition, material on the screen which will also be affected by gravityand will have a tendency to fall away from the screen and roll downwardsto the bottom of the drum. Preferably, the drum is tilted such thatparticles will generally move in the downstream direction. This rollingaction will also have a tendency to prevent the adherence of particlesto one another and thereby enable a more effective removal of drillingfluid through multiple rolling cycles. As a particle reaches adownstream position where the waste manifold 22 a is configured, as theparticle is drawn up the side of the drum due to the rotation of thedrum, it will enter the waste manifold 22 a where under the influence ofa radially inward vacuum pressure being applied through the wastemanifold be removed from the system. Other embodiments position a singleor additional waste manifold 22 b at the downstream end of the drum inthe approximate 6 o'clock position.

Further details on the operation and design of the RVT system aredescribed below.

Unibody Design

In a preferred embodiment, the RVT system 10 is a unibody design. Theunibody design generally reduces the number of components in the systemsuch that various sub-systems may have multiple functionalities so as toimprove the efficiency of manufacture. In particular, one objective ofthe unibody design is to provide both a sub-system's function while alsoproviding structural strength to the system while also reducing weight.

As shown in FIG. 8, individual components of a unibody design are shownin an exploded diagram.

Drum supports 12 a, 12 b are end plates defining openings for supportingand guiding a rotating drum. As shown, each drum support has a circularopening 12 c and a tab 12 d. The tab 12 d forms an end wall of the fluidmanifold as described below. The drum supports 12 a, 12 b also support adrum rotation system including at least one drive wheel 12 e and guidewheels 12 e′ that are positioned adjacent the opening 12 c to providesupporting and guide surfaces to a drum 26 (see FIG. 2). The drive andguide wheels are preferably adjustable to ensure alignment.

The two drum supports are interconnected by rods 12 f that provideappropriate spacing between the drum supports and which also assist inthe insertion of a drum within the drum supports during system assembly.

In addition, drive shaft 12 g interconnects drive wheels 12 e such thata driving force is applied simultaneously to both ends of the drum. Amotor 12 h is configured to one end of the drive shaft 12 g.

In the unibody design, the fluid manifold 14 includes bottom panel 14 a,top panel 14 b and outlet manifold 14 c. As shown, the bottom panel 14 aand top panel 14 b are connected to tab 12 d of the drum supports 12 a,12 b to define the structure of the fluid manifold. The outlet manifold14 c connects to the fluid manifold structure to provide a connectionpoint to a vacuum source, preferably through hose connections. The fluidmanifold 14 may also include internal partitions and/or baffles toenable different vacuum pressures to be applied to different zones ofthe fluid manifold (not shown). For example, it may be desired to applya vacuum pressure at the downstream end of the system sufficient tocause particle adhesion to the screen in order that such particles aredrawn upwardly to the waste manifold. In other zones, baffling may beused primarily to maximize the movement of fluid through the screen.

The cleaning manifold 16 is configured to the outer surface of the drumsupports 12 a, 12 b and includes a cleaning plenum 16 b and inletmanifold 16 a. Preferably the inlet plenum is inwardly tapered towardsits point of contact with the screen/drum so as to induce a venturieffect (ie. increased air speed and pressure decrease) as air movesthrough the inlet plenum. The inlet manifold 16 a provides a connectionpoint to an air pressure supply. The system may also include a spacerpanel 16 c to ensure that the entire outer surface of the drum iscovered and to enable spacing between the top of the fluid manifold andthe cleaning manifold if desired.

A cover 18 and cover support panel 18 a are configured to the drumsupport from the cleaning manifold through the 12 o'clock position tothe upper position of the fluid manifold (i.e. at the 4 o'clockposition). The cover may pivotally connect to the cover support so as toallow access to the outer surface of the drum. The cover support panel18 a will include an opening substantially corresponding to the lengthof the drum and sufficiently wide to enable screen replacement, as isexplained in greater detail below. The cover support panel 18 a alsoensures that the portion of the drum from the cleaning manifold throughto the fluid manifold is covered.

End Covers

As shown in FIGS. 3 and 5, at the upstream end A, an inflow coverassembly 28 covers the upstream end of the drum. The inflow cover isdesigned to seal against the rotating drum and support an inflow sluice28 a for the slurry of materials to be introduced into the rotatingdrum. As shown, the inflow cover assembly is connected to the drumsupport 12 a via an inflow mount 28 b that extends over and around thedrum 26. The inflow cover assembly is shown slightly recessed within thedrum 26. Appropriate gaskets (not shown) may be provided to improvesealing. In addition, as shown in FIG. 5, the inflow sluice 28 a may beoffset with respect to the bottom of the drum in a direction opposite tothe direction of drum rotation in order to deliver slurry as close tothe upstream edge of the fluid manifold as possible to maximize slurryresidence time over the fluid manifold.

As shown in FIG. 2, at the downstream end B, a waste manifold assembly22 covers the downstream end of the drum 26. The waste manifold assembly22 is designed to seal against the rotating drum 26 and to support awaste manifold 22 a and overflow waste manifold 22 b. As shown, thewaste manifold assembly is connected to the drum support 12 b via awaste manifold mount 22 c. Each of the waste manifold 22 a and overflowwaste manifold 22 b are designed for connection to a vacuum system.

As shown in FIG. 9, the waste manifold assembly 22 may include an innerwaste manifold 22 d connected to the waste manifold 22 a through thedownstream cover 22 e. The inner waste manifold is positioned to beoperatively located adjacent the inner surface of the drum 26 such thatsolids on the drum may be removed from the drum through inner wastemanifold 22 d and waste manifold 22 a under vacuum. As such, the innerwaste manifold 22 d has an opening 22 h and surfaces 22 i for placementnear the inner surface of the drum (i.e. generally convex at the ends).The spacing between inner waste manifold 22 d and the inner surface ofthe drum should be great enough to allow drill cutting particles toenter the drum while minimizing vacuum losses. Appropriate gaskets maybe provided on the inner waste manifold on the downstream surfaces tominimize these losses.

The overflow waste manifold 22 b includes an opening 22 k in the lowerpart of the downstream cover 22 e to enable larger particles that maynot be drawn up to inner waste manifold to be removed at a lowerposition of the drum. The overflow waste manifold is designed forconnection to a vacuum system and may also include one or more directingbaffles 22 j for directing larger particles through the opening in thedownstream cover to overflow waste manifold 22 b. In one embodiment, thesystem is only provided with the overflow waste manifold.

Drum

As shown in FIG. 10, the drum 26 is a cylindrical tube having anupstream end A and downstream end B with a plurality of openings 26 binterspersed throughout a middle section of the drum. The upstream endincludes a flange 26 a for engagement with axial support wheels 20 aconnected to the drum support 12 a that engage with the flange when thedrum is within the RVT system. Radial support wheels 12 e′ connected tothe drum supports 12 a, 12 b are provided at both the upstream anddownstream ends of the drum to provide radial support to the drum whenthe drum is within the RVT system.

As shown, the openings 26 b extend substantially across the length ofthe drum and provide a surface to which a screen assembly 30 isconnected to as described below.

The drum may be manufactured from metal, plastic or composite materials.In one method of manufacturing the drum, a pre-formed tube may be cut(eg. by laser or water cutting) to form the openings within the tubewithin the middle section C of the drum. Thereafter, a flange 26 a maybe attached to the upstream end A of the drum. The shape of the openingsand void space may be chosen to optimize both void space and structuralintegrity of the drum.

Screen and Screen Replacement

As shown in FIG. 10A, a screen assembly 30 is shown. In one embodiment,the screen assembly includes a screen 30 a, tensioning supportconnectors 30 b, 30 c and tensioning connectors 30 d (FIG. 10d ). Asshown in FIG. 3, a screen assembly may be connected to the drum throughcover 18. As shown, a rolled screen assembly 30 is mounted on drumsupports 12 a, 12 b via a support rod 30 e. The screen 30 a is partiallyunrolled such that one of the tensioning support connectors (eg. 30 b)is placed flush against the drum. One or more tensioning connectors 30 dare connected to the tensioning support connectors (preferablypre-attached) to secure the tensioning support connector against thedrum. The drum is then rotated such that the screen 30 a is unrolled andthereby covers the outer surface of the drum. As the drum completes afull rotation, the second tensioning support connector (eg. 30 c) willbe reached whereupon the two tensioning support connectors 30 b, 30 care connected together via the tensioning connectors 30 d to secure thescreen tightly against the drum.

In one embodiment, the screen may be provided with a plurality oftensioning bands 30 f that may provide additional support to the screenand minimize separation of the screen from the drum during use. Thetensioning bands and/or the tensioning connectors may includeappropriate mechanical tensioning systems such as a turnbuckle or leversystem (not shown) to provide further tensioning to the screen assembly.

As shown in FIG. 10B, the screen assembly may also comprise a pluralityof layers to provide structural support to a finer screen. For example,a base screen 70 of a coarser and stronger material may be used tosupport a finer screen 72 (shown only partially covering a coarsescreen) in order to prevent distortion and/or promote longevity in thefiner screen. The base screen 70 and finer screen 72 may be bondedtogether using appropriate adhesives.

After a screen assembly 30 has been configured to the drum and thescreen roll is removed, the cover 18 is closed and the RVT system may beoperated.

After a period of use, the screen will have to be replaced. The screenassembly 30 is removed from the drum by reversing the procedure followedto attach the screen assembly to the drum. An old screen may be rolledonto an empty screen roll for disposal. Access to the cover 30 may begained from a stand 24.

Screens may be substantively a single mesh size or may be different meshsizes that are positioned in different sections on the drum. That is, tothe extent that the system is configured to apply different vacuumpressures to different zones of the rotating drum, it may be desirableto have different screen sizes in those different zones. Accordingly, ascreen assembly may have different mesh sizes configured to anunderlying coarse screen in bands X, Y, Z as shown in FIG. 10A.

Distribution Plate

As shown in FIGS. 11, 11A and 11B, the RVT may be configured with adistribution plate 80 within the drum that can be used to facilitatemovement of material from one side of the drum to the other as well asto minimize the impact of solid materials dropping within the drum. Thatis, as material may rise up the drum before dropping, a distributionplate spanning a portion of the interior of the drum will enable thismaterial to move directly from approximately the 10 o'clock positionback to the 4 o'clock position. In one embodiment, as shown in FIG. 11,the distribution plate is a simple flat plate that extends between endsA,B of the drum and is mounted within the end covers of the wastemanifold assembly and inflow cover assembly. The distribution plate maybe vibrated by an appropriate vibration source such as an unbalancedmotor to effect vibration across the distribution plate 80. In anotherembodiment as shown in FIGS. 11A and 11B, the distribution plate 80 hasa hollow interior with a pliable upper surface 80 a. In this embodiment,a vibration source such as a pulsed air pressure may be introduced intothe interior of the plate so as to introduce a mild vibration toparticles on the surface 80 a to facilitate their movement across thesurface and to prevent clumping. Pulsed air pressure may be introducedthrough one or more conduits 80 b.

System Frame 20 and Drive System

As shown in FIGS. 1 and 2 for example, the RVT will include a supportsystem 20 to elevate the system from a work surface. In one embodiment,the system may be actively tilted so as to enable control of the angleof the drum to the horizontal and thereby control the relative speed bywhich material may move from the upstream A to the downstream end B ofthe drum. Similarly, the support system can be used to level the system.Appropriate linear motion actuators and motors 20 d and control systemsmay be provided to effect this control.

The drum 26 is rotated within the RVT system by a drive system thatincludes a drive motor 12 h and radial drive and support wheels 12 e.Wheels 12 e are interconnected via drive rod 12 g such that drive motor12 h rotates both wheels 12 e simultaneously as best seen in FIG. 8. Thedrive system includes an appropriate power source and controller toenable speed control of the drum although variable speed control is notnecessary for the operation of the system.

Assembly

FIG. 12 is an exploded view of the system and shows how a drum 26 isconfigured to the system during system assembly. As shown, an RVT 10will be typically angled downwardly from the upstream end A to thedownstream end B. The drum 26 is inserted into the upstream end of theRVT such that the flange 26 a rests upon the axial load wheels 20 a.Guide rods 12 f ensure alignment as the drum is inserted. As such, inthis embodiment, due to the angle of the RVT, the drum maintains itsposition within the RVT due to gravity. If it is desirable to run theRVT in a fully horizontal position, a second set of wheels (not shown)may be engaged with the flange to prevent axial movement of the drumwithin the RVT.

After the drum has been located, the waste manifold assembly 22 andinflow cover assembly may be configured to the RVT; however, in someembodiments, the waste manifold assembly may remain fixed. The inflowcover assembly is then connected to drum support 12 a. Appropriategaskets 26 f may be operatively configured to the inflow cover assembly,waste manifold assembly and drum supports for sealing. Prior to closing,a distribution plate may be inserted if the system is so configured.

The screen 30 is connected to the drum 26 as described above throughcover 18.

Vacuum Equipment

As shown in FIG. 14, the system is configured to appropriate vacuumequipment to enable separation of the solid and liquid components of theslurry. One or more vacuum sources 50 are configured to the fluidmanifold 14 and waste manifold assembly 22 in order to apply vacuumpressure to these systems. In addition, the waste manifold assembly isconnected to a solids/gas separator 52 and the fluid manifold isconnected to a liquid/gas separator 54.

In operation, as fluid is recovered from the fluid manifold, the fluidwill pass into the liquid/gas separator 54 where liquid will collect forremoval. In the case of drilling fluid, the drilling fluid willgenerally be recovered for return to the drilling operations.

Similarly, as solids are recovered from the waste manifold assembly 22,the solids will pass into the solids/gas separator 52 where solids willcollect for removal. In the case of drill cuttings, the drill cuttingswill be recovered for further treatment and/or disposal.

As shown in FIG. 14, each of the liquid/gas 54 and solids/gas 52separators are connected to the vacuum source 50, however, separatevacuum systems may be utilized. Appropriate valves 56 may be configuredto the piping system to individually control air flow through eachpiping system. Further, in order to preserve heat within the system,outflow 50 a from the vacuum 50 may be used as the air supply for thecleaning manifold 16. Thus, in this embodiment, the vacuum pump willdraw air through each of the fluid and waste manifolds (ie. by creatinga negative pressure) and the exhaust air from the vacuum is then used tocreate a positive pressure within the fluid manifold. As a result, asthe system is substantially sealed, air within the system will besubstantially recycled. It should however be noted that as a result ofresistances and leakages within the system, some make up air 50 b willbe required and/or an air outlet 50 c is required. Preferably, a degreeof air exchange is desired to decrease the humidity of the system aswell as to enable the removal of volatile gases and/or volatile organiccompounds (VOC). Appropriate gas sensors and/or valve and vents may beconfigured to the system to both monitor and control gas concentrationsin the event that unsafe concentrations of particular gases aremeasured. VOCs may be removed from the system in a controlled manner forsubsequent combustion. Importantly, and from an environmentalperspective, the subject system can be used to prevent the release ofenvironmentally damaging VOCs to the environment.

Furthermore, a substantially closed system will preserve heat whichdepending on atmospheric conditions may be helpful in increasing thetemperature of the system and thereby reduce fluid viscosities (in thecase of oil-based drilling fluids) and thereby enable finer screens tobe run. This may also be particular important when operating the systemin cold climates where the ambient air temperature may in the range of−30 to −40° C. in which case the closed system can maintain a highertemperature within the system which will have a positive effect on fluidviscosities (i.e. lower viscosities) within the system that will improveseparation efficiencies. The air may also be directly heated by anexternal heat source if desired (not shown). As noted above, as the airbeing used within the system will often contain volatile organiccompounds (VOCs), the VOCs may be directed to a combustionchamber/system 60 (eg. a furnace or diesel engine) where they are burntwithout being released to the atmosphere. In addition, this combustionmay be used as a heat source to provide heating to the RVT or otherequipment.

As also shown in FIG. 14, the system includes an electronic controlsystem (ECS) 80 that generally enables the speed of rotation and vacuumpressures within the one or more vacuum systems to be set. In theembodiment where the fluid manifold may have zones, the ECS may also beused to set the vacuum pressures in each zone. It should be noted thatwhile FIG. 14 shows a single vacuum system, separate vacuum systems maybe utilized with an appropriate manifold to enable the control of vacuumin each location of the system.

It should also be noted that the ECS may enable control of otheroperational parameters including the angle of tilt, the introduction ofair currents within the drum, vacuum pressures and other parameters thatmay be adjusted singly or in combination to effect a desired cleaninglevel.

Multiple RVT systems may also be configured in parallel to enable higherprocessing volumes. Systems may also be configured in series ifnecessary to enable processing in stages. RVT systems having differentdrum diameters and lengths may be used to provide control over a widerrange of processing parameters. That is, a smaller secondary system inseries may be used to provide additional cleaning to recovered drillcuttings.

Importantly, in the embodiment where a waste manifold only extends alonga portion of the drum, particles are subjected to a rolling motion asthey move up and fall down the rotating drum. This has the effect ofensuring that particles randomly come into contact with the drum andotherwise are continuously being separated from one another during theseparation process. In one embodiment, in order to prevent particlesfrom impacting with one another if they are dropping from a higherregion of the drum to a lower region of the drum, the interior of thedrum may be provided with a distribution plate 80 (as described above)extending across the length and width of the drum that absorbs theimpact and/or directs a falling particle from one side of the drum toanother. Experimentally, it has been observed that liquid-saturatedparticles subjected to a tumbling process in a gas environment (i.e. acombined solid/liquid/gas process within a rotating drum) will dry morerapidly (particularly within a heated or partially heated chamber) ascompared to a liquid/solid separation process as may be observed on ashaker screen where the particles are not subjected to movement througha gas phase.

Further still, as shown in FIG. 13, a compressed air source may beconfigured within or after the cleaning manifold to apply a highpressure air source to the exterior of the screen to assist in cleaningthe screen, if necessary. In particular, if a very fine screen is beingrun, additional cleaning force may be required to ensure that solidparticles do not adhere to the screen.

As shown in FIG. 13, a cleaning nozzle 16 m is configured after thecleaning manifold to apply a high pressure air to the exterior of thescreen. FIG. 13 also shows an embodiment of the cleaning manifold wherethe cleaning manifold is not connected to an air pressure system. Inthis case, with or without the cleaning nozzle 16 m, air will simply bedrawn through the cleaning manifold as a result of the generallynegative pressure exerted by the fluid and waste manifolds.

RVTA General Operation and Design

With reference to FIGS. 15-22, embodiments of a rotating vacuum table(RVTA) separator 100 are described. While the rotating table separatoris described as a system for separating drilling fluid and drillcuttings, it is understood that the RVTA may be used to separate otherfluids/solids from one another.

General Design and Operation

As shown in the Figures, a rotating table separator (RVTA) 100 generallyincludes a support frame 112, a rotating screen support 114 configuredto the support frame 112, a screen 116 supported by the rotating screensupport 114, a fluid manifold 118 configured to the underside ofrotating screen support 114, a waste manifold 120 operatively positionedabove the screen 116 surface and an inflow sluice 122 operativelypositioned above the screen surface. The RVTA may also include a cover124 connected to the frame 112 that is moveable from an open position(FIG. 16) to a closed position (FIG. 16A). In operation, the rotatingscreen support 114 and screen 116 rotate relative to the fluid manifold118, waste manifold 120 and inflow sluice 122. At least one vacuumsource 150 (FIG. 22) is configured to each of the waste manifold 120 andfluid manifold 118 to apply vacuum to the upper and lower sides of thescreen 116 respectively as the screen is rotating relative to each ofthe waste manifold 120 and fluid manifold 118.

A slurry of drill cuttings and drilling fluid is introduced onto thescreen 116 at a position of the rotating table 100 via the inflow sluice122. As shown in FIG. 16, the screen support 114 of the RVTA 100 isrotated in a clockwise direction such that the slurry is carried alongthe screen in the clockwise direction while vacuum is being applied toboth the fluid manifold 118 and to the waste manifold 120. Of course,the screen can be rotated in the opposite direction if the system is setup for counter-clockwise rotation.

For the purposes of illustration in this description, positions of theRVTA 100 are correlated to the positions of a clock with the “top” ofthe rotary table being generally referred to as the 12 o'clock position(designated XII in FIG. 16 together with III, VI and IX representingother clock positions). As shown, the waste manifold 120 is configuredto the top of the screen at approximately the 2 o'clock position and theinflow sluice 122 is configured to the top of the screen 116 at the 4o'clock position.

The fluid manifold 118 (FIG. 15) extends around the underside of therotary table and is designed to collect fluids passing through thescreen 116. Generally, the fluid manifold will only enable vacuum to beapplied between the inflow sluice 122 position and before the wasteposition i.e. from approximately the 4 o'clock position to approximatelythe 1 o'clock position. With vacuum being applied to the fluid manifold,liquid within the slurry is drawn through the screen leaving solidswithin the slurry on the upper surface of the screen. As the solidsreach the waste manifold 120, an upward vacuum pressure is applied bythe waste manifold to the upper surface of the screen 116 that causesthe solid materials to be removed from the screen through the wastemanifold 120. Thus, the RVTA provides a fluid removal phase between theinflow sluice 122 and waste manifold 120 and a solids removal phase atthe waste manifold.

In addition, by applying vacuum in opposite directions (i.e downwardswithin the fluid collection zone and upwards in the waste removal zone)at different positions of the rotary table 100, both fluids and solidsare effectively removed from the RVTA thus enabling continuous operationfor the separation of solids and liquids. Moreover, the application ofvacuum pressure in opposite directions during a single revolution of thescreen provides continuous cleaning of the screen as each section of thescreen passes the waste manifold during a single revolution whereby airis drawn upwardly through the screen to dislodge smaller particles thatmay have become lodged within the screen during the fluid removal phase.

In one embodiment of the RVTA, the RVTA may be made to vibrate in amanner similar to that of a conventional shaker in order to impartadditional separation forces on drilling fluid and drill cuttings. Inthis case, the drive system and/or frame may be mounted on a vibrationsource to impart a vibration to the screen. Thus, the RVTA can operatein a manner similar to that of a conventional shaker whilst stillproviding continuous cleaning of the screen which is not possible with aconventional shaker.

As shown in FIG. 16A, a vibration suspension and source 117 may beconfigured to the RVTA. In this case, the clearance between the inflowsluice and waste manifold may be increased relative to the screen asnecessary to prevent impact with the screen.

Additional details of the design and operation of the RVTA are describedbelow.

Frame 112

The frame 112 generally supports the rotating screen support 114 througha roller support system such as roller wheels 112 a supported on axles112 b. The frame may include a base 112 c and vertical support members112 d. One or more roller wheels 112 a will be actively driven by atleast one drive motor 112 e operatively connected to at least one of theroller wheels 112 a. It should be understood that various drivemechanisms can be employed including drive belts/chains/gears/sprocketsetc. as may be understood by those skilled in the art. However,preferably in order to ensure that the rotating screen support 114remains balanced on the drive system, if two drive motors are employed,it is preferred that such drive motors are configured to adjacentrollers (i.e at 90 degrees relative to one another) as opposed todiametrically opposed rollers. That is, as driven rollers may wear morequickly that non-driven rollers, it is preferred that the driven rollersremain in contact with the rotating screen support 114 as they wearwhich is ensured if the rollers are adjacent to one another on a fourleg frame system 112 as shown in FIG. 15.

In one embodiment, the frame 112 may also include means enabling thescreen 116 to be inclined during operation. If the system is to beinclined, it will generally be inclined in a direction such the wastemanifold 120 is at the lowest position such that gravity enhancesremoval of solid materials from the screen surface. Inclining meanscould include various hydraulic or mechanical tilting means that mayenable inclination of the system from 0 to about 30 degrees. As with theRVT, inclination can promote tumbling of particles through a gas phase.

As shown in FIGS. 16B and 16C, the frame may also include a centralspindle 112 f that is used for centering rotating screen support 114within the frame in which case the rotating screen support will includeappropriate supports 114 e and bearing 114 f.

Screen Support 114

The screen support 114 generally includes an outer support flange 114 athat engages with the roller wheels 112 a. The outer support flange 114a has an under surface that rests on top of the roller wheels 112 aallowing the outer support flange 114 a to rotate about a vertical axis.The screen support 114 also includes an outer flange ring 114 i, and aninner hoop 114 b connected to the outer flange ring 114 i via ribs 114c. In one embodiment, the inner hoop 114 b may be a flange that is alsosupported by additional roller wheels (not shown) or by spindle 112 f.

Additional inner hoops 114 d may be provided as necessary forappropriate screen support and structural stiffness.

Preferentially, the outer flange ring 114 i, outer support flange 114 aand inner hoop 114 b extend above the ribs 114 c such that when a screen116 is placed on top, the screen 116 is also below the outer supportflange 114 a and inner hoop 114 b, so as to prevent spillage of slurrymaterials off the sides of the system 100 during operation.

As shown, the screen support 114 is a ring with a void interior,however, it is understood that the screen support 114 may be a diskwithout an interior void opening adjacent the axis of rotation. In thiscase, the screen 116 would be a corresponding disk. Similarly, in thiscase the fluid manifold 118 would also be configured to the completeunderside of the disk.

Screen 116

The screen 116 is supported by the screen support 114 and corresponds inshape and size by the area defined by the inner dimensions of the outerflange ring 114 i and inner hoop 114 b. As shown in FIG. 18, the screen116 generally comprises an upper small mesh size screen 116 a adhered toa perforated backing 116 b that provides support and strength to thescreen. For the purposes of clarity, the drawings generally only showthe perforated backing 116 b.

In the case of a system designed for drilling fluid separation, thescreen will typically have a mesh size smaller than 200 mesh, typically200-400+ mesh. However, in other fluid/solid separations, larger screenmesh sizes (less than 200 mesh) may be used (eg. approximately 80 mesh).

In one embodiment, the upper screen 116 a is supported by a metalbacking material. In other embodiments, the screen may be configured toa polymeric backing material including rubbers or plastics.

The screen 116 may also be segmented into multiple sections as shown bydotted lines 116 c to facilitate screen replacement.

Fluid Manifold 118

The fluid manifold 118 is configured to the underside of the rotatingscreen support 114 and connected to the frame 112 with brackets 118 h soas to collect fluids passing through the screen 116. In the design shownin FIG. 15, the fluid manifold 118 is configured to the completeunderside of the rotating screen support 114 primarily for the purposesof manufacturing simplicity but also to allow the capture of any strayfluids that remain adhered to the screen, rotating screen supportincluding the ribs. However, importantly, the fluid manifold need onlybe configured from the slurry entry point (i.e. slurry sluice 122) tothe waste manifold 120. Preferably, at the waste manifold position, aventuri plenum 118 b is provided for direct air flow from the undersideof the fluid manifold 18 to the screen.

The fluid manifold will preferably have a non-horizontal or inclinedlower surface such that fluids contacting the fluid manifold willnaturally flow to the fluid manifold outlet 118 a. Vacuum pressure isalso applied through fluid manifold outlet 118 a. In order to preventbuild-up of materials within the fluid manifold, cleaning systemsincluding compressed air as described below may be provided within fluidmanifold to assist in the removal of such materials.

FIGS. 17 and 17A show a fluid manifold with relatively shallow sides andthe fluid manifold outlet configured to one side of the fluid manifold.However, it is understood that the fluid manifold can be constructedwith a substantially greater depth and with steeper sides so as tofacilitate the flow of fluid from the fluid manifold. Similarly, thefluid manifold outlet can be configured at any lower position of thefluid manifold. It is understood that the height of the frame can beadjusted to accommodate different heights of fluid manifolds.

In order to enable different strengths of vacuum to be applied todifferent zones of the fluid manifold, the fluid manifold may alsoinclude a series of baffles that restrict air flow through the fluidmanifold. That is, in one embodiment, it may be preferred to apply astronger, higher volume/air flow vacuum force through the sections ofthe fluid manifold closest to the waste manifold to ensure finalcleaning of the solids before removal. Accordingly, baffles can beutilized to ensure different forces in different zones.

In one embodiment, as shown in FIGS. 17B, 17C, 17D, baffles 118 c fullyseal off different zones of the fluid manifold. In this case, the fluidmanifold 118 would be provided with individual outlets 118 a′ for eachzone and each connected to a common manifold 118 d which is connected tothe vacuum source. In addition, as shown, each outlet 118 a′ may beprovided with a throttle 118 e and throttle control 118 f be configuredto each outlet allowing the vacuum in each zone to be controlled.

In those zones where fluid is not being collected, appropriate venturiplenums 118 b will be provided to enable upward air flow through thescreen and into the waste manifold 120.

As shown in FIGS. 17-17D, in order to ensure effective “sealing” of onezone to another, a horizontal plate 118 g is provided atop a baffle thatis designed to engage with at least one rib 114 c of the screen support114 at any particular moment during screen rotation. That is, in orderto ensure that different vacuums can be applied to different zones,there must be minimal inter-zone openings to enable a desired vacuumpressure to be maintained in one zone relative to another. Thehorizontal plates 118 g will generally have tapered sides that aresubstantially parallel to ribs 114 c passing over them.

FIG. 16D shows a cross section of the RVTA with the cover 124 in theclosed position.

Waste Manifold 120

The waste manifold 120 generally comprises a plenum for operativeengagement with the upper surface of the screen. As shown in FIG. 19,the waste manifold 120 includes an inlet plenum 120 a and conveyingplenum 120 b.

The inlet plenum 120 a has an upstream edge blade 120 c and a downstreamedge blade 120 d that are generally parallel to one another andtransverse to the direction of screen movement when positioned on thescreen. The upstream edge and downstream edge include resilientlyflexible blades 120 e whose respective heights may be adjusted relativeto the screen. Typically, the upstream edge blade will be positionedhigher than the downstream edge blade to enable any larger particles topass into the waste manifold without causing damage to the screen.

The conveying plenum 120 b is connected to the inlet plenum in a mannerto facilitate the generally upward movement of particles through theinlet plenum 120 a to the generally horizontal movement of particlesthrough the conveying plenum 120 b in a manner that maintains movementthrough both. As such, it is preferred that the inlet plenum promotescyclonic flow through the conveying plenum by means of a tangentialinflow direction relative to the conveying plenum. This feature isimportant to prevent or minimize the deposit of material within theconveying plenum. The conveying plenum may also have tapering surfaces120 f to assist in the creation of cyclonic flows within the wastemanifold.

In one embodiment, the waste manifold includes a second manifoldadjacent the primary waste manifold that will serve primarily to induceairflow through the screen to effect thorough screen cleaning. A secondwaste manifold (not shown) may be substantially identical to the primarywaste manifold and may simply be located in a downstream position, forexample at the 3 o'clock position. A compressed air manifold (not shown)may also be configured to the underside of the screen in conjunctionwith the second waste manifold.

The waste manifold is preferably pivotable between an engaged anddisengaged position to enable ready access to the screen forreplacement. As shown in FIGS. 16 and 19, the conveying manifold 120 bmay be supported by a support member 120 g that allows lifting andpivotal movement of the waste manifold between an engaged and disengagedposition.

Inflow Sluice 122

The inflow sluice 122 operates to distribute a liquids/solids slurry onthe screen. As shown in FIG. 21, the inflow sluice is generally aninclined pan 122 a having sides 122 b that spread the slurry over thewidth of the screen. An inflow duct/hose 122 c receives the slurry froman appropriate source. The inflow sluice can be lifted and pivoted intoposition by sluice support arm 122 d connected to the frame 112.

In one embodiment, the inflow sluice 122 further includes a largeparticle entrapment system 122 e (LPES) that can prevent particles abovea particular size to drop onto the screen which can be helpful inprolonging the life of a screen. The LPES, in one embodiment, includes aplurality of parallel tines 122 f that are spaced apart at a desiredspacing and that are parallel to the screen. A bar 122 g provides an endstop at the end of the tines. As larger particles travel down theinclined pan, the spacing of the tines 122 f prevents such particlesfrom dropping on to the screen.

The LPES will also preferably be detachable from the inflow sluice toenable an operator to periodically remove the system for emptying.Generally, the LPES will not require frequent emptying but periodicmonitoring by personnel can prevent potentially damaging particles fromcontacting the screen.

Cover 124

The system will preferably include a cover 124 that covers the uppersurface of the screen during operation. The cover 124 serves to preventthe escape of potentially dangerous gases released from the slurry aswell as to provide venting orifices that may be positioned to assist inthe flow of air through the screen at particular locations.

The cover is preferably connected to the frame 112 in such a manner toenable ready access to the screen for replacement such as by a hingingmechanism. The cover or sections of the cover are preferably transparentto enable operators to observe the screen.

One or more venturi plenums 124 a may form part of the cover. As shownin FIG. 20, the venturi plenums 124 a generally correspond to the widthof the screen and form a passageway between the outside of the cover andthe screen. The venturi plenums may be vertically adjustable such thatthe distance between the bottom end of the plenum and screen can beadjusted. In operation, if higher or lower airflow is required at aparticular location on the screen, the height of the plenum can beadjusted to cause an increase or decrease in airflow that can effectfluid transport through the screen. Other figures show multiple venturiplenums.

The cover may also be provided with a series of air orifices 124 b thatensure sufficient air flow to the screen when the cover is closed.

Operation and Auxiliary Equipment

As shown in FIG. 22, auxiliary equipment required to operate the systemincludes appropriate gas/liquid separators 154, gas/solid separators152, vacuum pumps 150 and electronic control 180 systems configure toone or more RVTAs.

The gas/liquid and gas/solids separators are configured to the fluid andwaste manifolds respectively to prevent contamination of the vacuumpumps with fluids and solids.

In a typical drilling operation, the system is operated with sufficientvacuum pressures and air flow rates to effect high fluid/solidseparations (typically greater than 90% and more preferably greater than95% fluid recovery from the cuttings) with a single unit for aparticular drilling fluid flow rate. Residence time of particles on thescreen can be adjusted by screen rotation rate and will be balancedagainst air flow rates within the fluid removal zone, the processingvolume and slurry characteristics. Localized air pressure flow throughthe screen may be fine tuned by the venturi plenums.

For example, and in the case of well drilling, at a higher rate ofpenetration (ROP) where drill cuttings particle sizes may be bigger andthe mass of particles relative to a volume of drilling fluid is higher,for a given air flow rate, the speed of rotation may be increased. Thatis, for a situation where drilling particles are larger, the surfacearea of cuttings covered with drilling fluid may be relatively lowercompared to a situation with finer drill cuttings. Moreover, the surfacetension of drilling fluid adhered to a drill cutting is generally lowerwith a larger radius particle size (will also depend of the shape androughness), thus the vacuum required for separation is less and hence,the residence time can be decreased by a faster screen rotation.

Conversely, if ROP is slower and particle sizes are smaller, for a givenair flow rate, the speed of rotation may be slowed to ensure moreeffective separation of fluid from the smaller particles whose relativesurface is substantially higher within a volume of fluid.

It should be noted, however, that other operational parameters may beconsidered including the angle of tilt, the introduction of air currentsabove or below the screen to induce tumbling, vacuum pressures and otherparameters that may be adjusted singly or in combination to effect adesired cleaning level.

As also shown in FIG. 22, two or more RVTAs 100 may be configured inseries to effect a higher degree of separation. In this case, a largerRVTA 100 may provide primary solid/liquid separation whereas a smallerRVTA unit 100 a may be used for additional cleaning of the solidsrecovered from the larger RVTA. In this case, the primary separator maybe run with a very fine mesh to ensure that high quality fluid isrecovered. In this case, the solids recovered from the waste manifoldmay be wetter when introduced into a secondary separator. The secondseparator would ensure that the solids recovered off the secondaryseparator are dry.

The electronic control system (ECS) 180 will generally enable the speedof rotation and vacuum pressures within the one or more vacuum systemsto be set. In the embodiment where the fluid manifold may have zones,the ECS may also be used to set the vacuum pressures in each zonethrough the manifold valves as described above. It should be noted thatwhile FIG. 22 shows a single vacuum system, separate vacuum systems maybe utilized with appropriate piping and valve system to enable thecontrol of vacuum in each location of the system. The ECS may alsocontrol the angle of tilt.

The system may also be connected with the RVT system as described above.In addition, multiple RVTs and/or RVTAs systems may also be configuredin parallel and/or in series.

Other Design Considerations Screen Configured to Inside of Drum

As shown in FIG. 23, a screen 222 may be configured to an inside surfaceof a drum 212 via a support frame 224 that is used to bias the screen tothe interior of a drum. Generally, a support frame will include twocircular support hoops 224 a, 224 b and series of hoop supports 224 cthat interconnect the support hoops. In one embodiment, the supporthoops 224 a, 224 b are manufactured from a spring steel as an open hoopand having a diameter slightly larger than the inner diameter of thedrum 212 such that when configured to the interior surface of the drum,the support frame biases the screen against the drum. In otherembodiments, the support frame may be rigidly connected to the drumthrough appropriate fastening devices including bolts and/or clips. Thesupport hoops 224 a, 224 b will generally be fabricated with a lowvertical profile so as to not interfere with the passage of drillingfluid and cuttings over the screen towards the downstream end B of thedrum. However, the hoop supports 224 c may have a higher verticalprofile in order to assist in the holding cuttings against the screenduring rotation of the drum. To facilitate ease of installation and/orreplacement multiple screens 222 and support frames 224 may be utilized.

Venturi and Manifold Cleaning (Anti-Caking)

In another embodiment, the fluid and waste manifolds are configured withone or more air nozzles 245 (FIG. 25) that may be configured to acompressed air system 16 a (FIG. 14) to assist in enhancing air flowthrough the manifolds. Generally, if compressed air is incorporated, thepurpose of the compressed air is primarily to prevent the build-up offines on the lower surfaces of the manifold in the event that vacuum airflow through the system is not sufficient to prevent the build up offines. As such, the compressed air system may only be operatedintermittently. The cleaning system may also utilize high pressurefluids that may be circulated through the system. Recovered drillingfluid may be used as a cleaning fluid in some circumstances.

That is, during operation, the system may be periodically flushed withcompressed air or fluids to prevent the build up of any fines on themanifold surfaces. In particular, as the flow of drill cuttings to solidseparation equipment is generally cyclical during drilling as mud pumpsare turned on and off to allow new sections of pipe to be added to adrill string, the system may periodically apply compressed air or fluidsto assist in flushing the manifold.

FIG. 24 shows an embodiment where the waste manifold 218 z is tapered soas to facilitate the downward flow/movement of recovered drill cuttings.A plurality of bleed ports 218 y is also shown which may be used as ameans of introducing additional air flow into the manifold. A deliverychute 250 without an open upper surface is also shown. An overflow chute240 (FIG. 25) may also be provided.

Scoops and Air Path Design

FIGS. 25-30 describe another embodiment of an RVT 210. In thisembodiment, the inner surface of the drum is provided with a series ofscoops 270 that collect and carry drill cuttings to the waste manifoldwhile applying vacuum to the drill cuttings within each scoop 270. In apreferred embodiment, the scoops extend longitudinally along the lengthof the drum; however, smaller scoops may be utilized and may bedistributed differently about the drum. As shown, the scoops willtypically include two end walls 270 a, a back wall 270 b and a base wall270 c and defining an open face 270 d.

In this embodiment, as a slurry of drill cuttings/drill fluid flow ontothe rotating drum, the rotation of the drum will cause the slurry to becontained within the scoops, thereby lifting a volume of drillcuttings/drill fluid. As above, a fluid manifold applies an outwardradial pressure to the inner surface of each scoop such that drillingfluid is drawn through the screen. In this case, the waste manifold 218z is configured to the drum at a location past vertical (eg. about 30degrees to vertical) due to the presence of the back wall 270 b and inorder to enable the cuttings to fall by gravity and vacuum into thewaste manifold.

As best shown in FIG. 26, which is a cross-sectional segment of thisembodiment, the waste manifold 218 z will preferably include sealingarms 218 m,n on the upstream and downstream sides of the waste manifoldto ensure that the internal volume 218 y is generally sealed assuccessive scoops pass by the waste manifold. That is, as shown at agiven moment, the sealing arms 218 m,n are each in contact (or veryclose to being in contact) with two (or more) back walls 270 b of two ormore scoops, such that the waste manifold 218 z is not directly open tothe atmosphere. Appropriate wear surfaces may be provided.

As described above, as a scoop enters the waste manifold and thepreceding scoop opens the path to vacuum, a reversal in vacuum pressureoccurs such that cuttings contained in the scoop fall into the wastemanifold and air flow is reversed through the screen to clean it. Afterthe cuttings have fallen out of the scoop, the scoop continues itsrotation through the sealing arm 218 n which similarly provide a seal atthe downstream side.

Also, as shown in FIG. 26, the fluid manifold 216 z may include one ormore baffles within its volume to assist in the distribution of vacuumin the fluid manifold. That is, it may be desirable for a higher vacuumpressure to be applied to the downstream B side 216 h of the fluidmanifold in which case the baffles 216 y may restrict air flow behindthe baffles thereby reducing vacuum pressure at those locations.

As shown in FIG. 26, in one embodiment, the drum is not a continuousscreen but instead includes openings 260 to support a plurality ofsmaller generally rectangular screens positioned within a scoop (notshown). The screens may be connected to the drum and/or openings 260 byany suitable means as known to those skilled in the art.

Similarly, as shown in FIG. 26A, the fluid manifold may also be providedwith an upper drum contacting surface 216 h having a plurality ofopenings 216 i. This enables a higher vacuum pressure to be specificallyapplied within a scoop and can induce high velocity air flow through thescoop as the scoop moves past an opening 216 i. As shown in FIG. 27, theair flow through a scoop will initiate as the upper portion of a scooppasses an opening (see FIG. 27(A)). The air flow will then successivelypass through the middle and lower sections of the scoop (see FIGS. 27(B)and (C)). If each of the scoops is aligned with respective fluidmanifold openings, the fluid manifold will be effectively closed off tothe screens at regular positions in the rotation cycle. Thus, initially,as a scoop begins to pass the fluid manifold opening 216 i, the initialair flow through the scoop will be high as only a small slit of screenwill be exposed to vacuum. As a greater amount of screen is exposed, theair velocity will decrease and then increase again as the scoop passesthe opening 216 i. This will have the effect of applying a substantiallyhigher pressure to the surfaces of the drill cuttings in a pseudo-pulsedmanner.

In another embodiment as shown in FIGS. 28 and 29, the scoops may beprovided with a series of bleed holes 270 e along the back wall 270 b ofscoop 270 to provide an alternate path to air flow through the scoop. Inthis case, the bleed holes 270 e enable multi-directional flow of airthrough the scoops as the scoops move past an opening 216 i as shown inFIG. 29.

In another embodiment, the drum 212 is provided with additional openings260′ (FIG. 30) outside a scoop. This particular format may promote fluidremoval particularly on the lower surfaces of the drum.

Drilling Rig Operation

Table 1 shows representative cutting volumes (CV) and drilling fluid(DF) flow rates (low, medium and high) for varying rates of penetration(ROP) (10, 20 and 30 m/hr) for different well diameters (6, 9 and 12inches respectively) when drilling. The CV value indicates the volume ofcuttings that may be introduced into and thus processed within the drumper minute and DF flow rate indicates the volume of DF passing into thefluid manifold per minute. As both CV and drilling fluid flow ratesincrease, the size (length and diameter) of the RVT may need to beincreased or require additional systems to be run in parallel. Thefollowing assumes a drum having an internal diameter of 1 m and a lengthof 2m and that the average volume % of cuttings in returned drillingfluid is approximately 0.15-0.8 vol %.

TABLE 1 Cuttings Volume and Flow Rates for Varying ROP Well Size(inches) Well Area (in²) 6 in (0.1524 m) 9 in (0.2286 m) 12 in (0.305 m)28.3 in² (0.018 m²) 63.6 in² (0.041 m²) 113 in² (0.073 m²) Low DF FlowRate 2 m³/min 2 m³/min 2 m³/min Low ROP (10 m/hr) CV = 0.18 m³/hr = 3l/min CV = 0.41 m³/hr = 6.8 l/min CV = 0.73 m³/hr = 12 l/min Mid DF FlowRate 3 m³/min 3 m³/min 3 m³/min Medium ROP (20 m/hr) CV = 0.36 m³/hr = 6l/min CV = 0.82 m³/hr = 13.6 l/min CV = 1.46 m³/hr = 24 l/min High DFFlow Rate 5 m³/min 5 m³/min 5 m³/min High ROP (30 m/hr) CV = 0.55 m³/hr= 9 l/min CV = 1.23 m³/hr = 20.5 l/min CV = 2.19 m³/hr = 36 l/min CV =cuttings volume

For example, in a 1 m diameter drum having a 2 m length, the totalsurface area of screen is approximately 6.28 m². If the fluid manifoldextends from the 4 o'clock to 9 o'clock positions, 41% or 2.6 m² ofscreen will have vacuum pressure being applied to it at a given moment.If the drum is rotating at 6 rpm, the screen is moving at 19 m/min, thusexposing the slurry to 38 m² of clean screen per minute.

Liquid studies were undertaken to determine the relative rates of flowof liquid through different size screens with different applied vacuumand with varying hydrostatic pressures on the top-side of a screen. Thestudies were completed in a test cell having a known area and theresults extrapolated to the RVT design.

Test 1—Water Flow Study

A test cell was built that included a water reservoir and a valvedoutlet at the bottom of the reservoir supporting a small section ofscreen. The underside of the outlet was configured to a lower reservoirand to a vacuum source. The valve could be opened and closed at theinitiation and termination of each experiment.

As the area of the screen was relatively small compared to the volume ofwater, a relatively consistent hydrostatic pressure on the screen wasmaintained throughout each experiment.

Individual experiments included adjusting the height of water in theupper reservoir, the screen size (mesh) and the vacuum pressure tomeasure the flow rate of liquid through the screen for a fixedhydrostatic pressure, screen size and vacuum pressure.

Tables 2 and 3 show a comparison of liquid flow rates for a 200 and 325mesh screen, respectively. For the purposes of calculation, it wasassumed that a liquid contacting a rotating screen from a central inletwill disperse across the screen such that the liquid height will begreatest at the middle relative to the inlet and lower as the distancefrom the inlet becomes greater. In other words, a liquid contacting ascreen will generally disperse across the screen such that thehydrostatic pressure of the liquid against the screen will be greatestwhere the height of the liquid is greatest and lower where the height ofthe liquid is lower. The dispersion profile of the liquid was assumed tobe 50 mm in a central zone (A), 25 mm in a middle zone (B) and 2 mm in aperipheral zone (C). Further, it was assumed that the total area of eachof zones A, B and C were 0.04, 0.12 and 0.18 m² respectively.

TABLE 2 Water Flow through 200 Mesh Screen having Zones A, B, and C atdifferent Applied Vacuum Pressures Screen Mesh 200 Screen Mesh 200Screen Mesh 200 Vacuum = ambient Vacuum 2 = 250 Pa Vacuum 3 = 500 PaZone (no vacuum applied under screen) applied under screen applied underscreen A = 0.04 m² 11 * 13.5 * 16 * B = 0.12 m²   23.5 * 33.5 * 41 * C =0.18 m² 10 * 37 *   51 * Total (liters/second) 44.5 84   108   (totalflow through Zones A, B, C) Total (m³/minute)  2.6 5.0   6.5 (total flowthrough Zones A, B, C) * total liters/s flow of water through Zone

TABLE 3 Water Flow through 325 Mesh Screen having Zones A, B, and C atdifferent Applied Vacuum Pressures Screen Mesh 325 Screen Mesh 325Screen Mesh 325 Vacuum = ambient Vacuum 2 = 250 Pa Vacuum 3 = 500 PaZone (no vacuum applied under screen) applied under screen applied underscreen A = 0.04 m² 9 * 30.5 * 13 * B = 0.12 m² 19 *  27.5 *   33.5 * C =0.18 m² 8 * 30.5 * 42 * Total (liters/second) 36   69   88.5 (total flowthrough Zones A, B, C) Total (m³/minute) 2.2 4.1   5.3 (total flowthrough Zones A, B, C) * total liters/s flow of water through Zone

Tables 2 and 3 show that as hydrostatic pressure within the test cellincreases, the flow rate of liquid through the screen increases. Thedata also show that the flow rate is generally proportional to thesquare root of the height. Similarly, as vacuum is increased, the flowrate for a given hydrostatic pressure increases. It was noted that asscreen pore size decreased, higher vacuum was required to effect fluidtransport across the screen.

These results were based on the assumption that liquid transport acrossthe screen occurs predominantly towards the upstream end A of the drumand the hydrostatic pressure drops towards the downstream end B of thedrum. Importantly, these results show that a relatively small area ofthe drum (eg. 0.34 m²; zones A, B, C) is capable of processingapproximately 4 m³/min of liquid (water) with only 250 Pa of vacuum.This is substantially smaller than the total area of screen availablethat is under vacuum at a given moment as described above. Accordingly,the subject system removes a relatively high percentage of fluid towardsthe upstream section of the RVT whereas the downstream section removes arelatively smaller volume of fluid but results in a substantially lowerfluid retained on cuttings wt % as compared to conventional shakers. Inother words, the upstream section results in “bulk” fluid removalwhereas the downstream section provides an effective “finishing” or“polishing” of the solid particles resulting in solid particles with arelatively high degree of dryness. In this sense, polishing refers tofluid removal as opposed to solid particle smoothing.

Although the present invention has been described and illustrated withrespect to preferred embodiments and preferred uses thereof, it is notto be so limited since modifications and changes can be made thereinwhich are within the full, intended scope of the invention as understoodby those skilled in the art.

1-21. (canceled)
 22. A solids/liquid separation system for separatingsolids and liquids within a slurry from one another, the separationsystem comprising: a screen operatively connected to a supporting frame,the screen supporting the slurry on an upper surface of the screen whenthe screen rotates about a vertical axis of rotation and where thescreen is a generally horizontal circular disk; a fluid manifoldoperatively connected to a lower surface of the screen and wherein thefluid manifold is configured to enable a vacuum pressure to be appliedin a first direction and to a first portion of the screen while thescreen is rotating to convey fluids through the screen; a cleaningmanifold operatively connected to an upper surface of the screen andwherein the cleaning manifold is configured to enable an air flowpressure to be applied to a second portion of the screen in a seconddirection generally opposite to the first direction while the screen isrotating; wherein the vacuum pressure in a first direction draws fluidthrough the screen into the fluid manifold and the air flow pressure inthe second direction induces air flow through the screen in the seconddirection to clean the rotating screen.
 23. The separation system as inclaim 22, wherein the cleaning manifold removes solid material on theupper surface of the screen.
 24. The separation system as in claim 22,further comprising an inlet sluice for introducing and distributing aslurry of solid/liquid onto the screen.
 25. The separation system as inclaim 22, further comprising a cover operatively connected to an upperside of the screen.
 26. The separation system as in claim 22, furthercomprising at least one vacuum system connected to each of the fluid andcleaning manifolds.
 27. The separation system as in claim 26, furthercomprising a gas/liquid separator between the fluid manifold and thevacuum system.
 28. The separation system as in claim 22, furthercomprising a gas/solids separator connected between the cleaningmanifold and the vacuum system.
 29. The separation system as in claim22, wherein the fluid manifold extends at least 270 degrees around anarea of the screen.
 30. The separation system as in claim 22, furthercomprising a drive system connected to the screen and supporting frameto effect rotation of the screen relative to the supporting frame. 31.The separation system as in claim 30, wherein the screen includes ascreen support connected to the drive system and the screen isconfigured to a top of the screen support.
 32. The separation system asin claim 31, wherein the screen support includes an outer support flangeadapted for rolling contact with the frame, an inner ring and aplurality of ribs connecting the outer support flange and inner ring andwherein the plurality of ribs support the screen at a level below upperedges of the outer support flange and inner ring to contain a slurry onthe replaceable screen during operation.
 33. The separation system as inclaim 22, wherein the fluid manifold includes at least one baffle forsectioning the fluid manifold into zones enabling application ofdifferent vacuum pressures into each zone during operation.
 34. Theseparation system as in claim 33, wherein the fluid manifold includes atleast two zones having separate outlets.
 35. The separation system as inclaim 34, wherein at least one separate outlet includes a throttleenabling the adjustment of vacuum pressure within at least one zone. 36.The separation system of claim 22, further comprising a vibration systemoperatively connected to the screen to effect vibration of the screen.